1. Field of the Invention
The present invention generally relates to an optical module, a method for producing the same and a holder for the optical module. More specifically, the invention relates to an optical module suitable for high-speed and large-capacity optical communication using an optical fiber, a method for producing the same and a holder for the optical module.
2. Description of the Background Art
In recent years, the request for optical fiber communication technology using optical fibers increases as the transmission speed and capacity for data communication increase. A typical optical module for such optical fiber communication comprises: a package called CAN package housing therein a photoelectric transfer element (e.g., a package housing therein a semiconductor light emitting element, such as a semiconductor laser, or a semiconductor light receiving element, such as a photodiode); a ferrule for holding an end face of an optical fiber; a lens; and a holder for housing therein them.
In such an optical module, a photoelectric transfer element in the photoelectric transfer element package is optically coupled with the optical fiber, which is held by the ferrule, via the lens to enable optical communication.
As examples of such optical modules, there are proposed optical modules disclosed in Japanese Patent Laid-Open Nos. 10-300994 and 2002-43675. In these optical modules, a photoelectric transfer element package, a ferrule and a lens are separated, so that an aligning operation for aligning the optical axes of the respective parts with each other must be carried out when the parts are housed in a holder. Therefore, in these optical modules, working and assembling efficiencies are not good.
Therefore, the inventor has diligently studied and proposed an optical module wherein a lens and a holder are formed of a plastic by integral molding (Japanese Patent Application No. 2003-026656). In such an optical module, since it is not required to align the optical axis of the lens with the axis of the holder, it is possible to facilitate the assembly of the optical module, so that it is possible to improve the production efficiency of the optical module.
As a conventional method for aligning a holder with a photoelectric transfer element, there is used an aligning method called active alignment for determining the optimum position of a photoelectric transfer element by actually causing the photoelectric transfer element to emit or receive signal light. In such a method, it is required to carry out alignment with respect to all of three axes of X- and Y-axes perpendicular to an optical axis and Z-axis parallel to the optical axis.
Therefore, the inventor has diligently studied and considered that, if such alignment in directions of three axes is simplified, it is possible to reduce the number of assembling steps, and it is possible to make the advantageous effects of the above described optical module with lens-integrated holder more effective. Thus, the inventor has made the present invention.